For most of the summer, the primary obstacle preventing Clay Buchholz from pitching again this season was a stress fracture in his lower back. Now, though, the right-hander's biggest enemy is time. Buchholz unleashed 30 pitches from the bullpen mound at Fenway Park yesterday, his first full-fledged side session since he was shut down from throwing in mid-July. And when he was through, the starter was encouraged by being able to throw each of his pitches at about 75-80 percent of his usual effort level without discomfort. Next up is another bullpen session, or maybe a simulated game, either tomorrow or Tuesday. "Had no issues with the back. It felt fine," Buchholz said. "If anything, the arm strength's not quite there with the four-seamer (fastball). But there are no issues, as far as the back goes. I'm pretty optimistic."